Giúp e với . e cảm ơn ạ
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bạn đăng tách ra tầm 10 câu mỗi lần đăng nha, chứ dài ntnay ngại làm lắm~
e có tách 3 bài ra rồi ạ, phiền anh/chị/bạn giúp e với ạ, e cảm ơn ạ
a)\(-1,6:\left(1+\dfrac{2}{3}\right)=-1,6:\dfrac{5}{3}=-\dfrac{8}{5}.\dfrac{3}{5}=\dfrac{-24}{25}\)
b)\(\left(\dfrac{-2}{3}\right)+\dfrac{3}{4}-\left(-\dfrac{1}{6}\right)+\left(\dfrac{-2}{5}\right)=-\dfrac{2}{3}+\dfrac{3}{4}+\dfrac{1}{6}-\dfrac{2}{5}=\dfrac{-40+45+10-24}{60}=\dfrac{-9}{60}=\dfrac{-3}{20}\)
c)\(\left(\dfrac{-3}{7}:\dfrac{2}{11}+\dfrac{-4}{7}:\dfrac{2}{11}\right).\dfrac{7}{33}=\left(\dfrac{-3}{7}.\dfrac{11}{2}+\dfrac{-4}{7}.\dfrac{11}{2}\right).\dfrac{7}{33}=\left[\dfrac{11}{2}\left(\dfrac{-3}{7}+\dfrac{-4}{7}\right)\right].\dfrac{7}{33}=\dfrac{-11}{2}.\dfrac{7}{33}=\dfrac{-7}{6}\)
d)\(\dfrac{-5}{8}+\dfrac{4}{9}:\left(\dfrac{-2}{3}\right)-\dfrac{7}{20}.\left(\dfrac{-5}{14}\right)=\dfrac{-5}{8}-\dfrac{4}{9}.\dfrac{3}{2}+\dfrac{1}{8}=\dfrac{-5}{8}+\dfrac{1}{8}-\dfrac{2}{3}=-\dfrac{7}{6}\)
Sửa đề: \(\dfrac{7}{x+5}-\dfrac{x}{5-x}=\dfrac{-x^2}{25-x^2}\)
\(\Leftrightarrow7\left(x-5\right)+x\left(x+5\right)=x^2\)
\(\Leftrightarrow7x-35+5x=0\)
=>12x=35
hay x=35/12
1:
(SAB), (SBC) vuông góc (BAC)
=>SB vuông góc (ABC)
AC vuông góc AB,SB
=>AC vuông góc (SAB)
=>AC vuông góc BH
mà SA vuông góc BH
nên BH vuông góc (SAC)
=>BH vuông góc SC
mà SC vuông góc BK
nên SC vuông góc (BHK)
c: (SH;(BHK))=góc SHK=(SA;BHK)
BC=BA/cos60=2a
SC=căn SB^2+BC^2=ăcn 5
SB^2=SK*SC
=>SK=a*căn 5/5
SA=căn SB^2+AB^2=a*căn 2
SB^2=SH*SA
=>SH=a*căn 2/2
sin SHK=căn 10/5
=>góc SHK=39 độ
e: 7x<=9x-5
=>7x-9x<=-5
=>-2x<=-5
=>x>=5/2
f: \(\Leftrightarrow7x-5< 8\left(3x-1\right)-4\left(2x+4\right)\)
=>7x-5<24x-8-8x-16
=>7x-5<16x-24
=>-9x<-19
hay x>19/9
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